I. Field of the Invention
The invention generally relates to mobile telephone systems and in particular to service provider selection in a mobile telephone system.
II. Description of the Related Art
Satellite-based mobile telecommunications systems are being developed that allow a mobile communications subscriber unit such as a mobile telephone to be used almost anywhere in the world. In one system, illustrated in FIG. 1, a fleet of low earth orbit satellites are used along with a set of ground base stations 10 called "gateways". Signals are transmitted from a subscriber unit 12 to satellites 14 (shown as a single satellite for ease of drawing), then relayed down to gateway 10 for routing to one of a set of local service providers, generally denoted 16, which provide an interconnection to local land line telephone networks or other communication networks operated by a service provider. Depending upon the nature of the communication, the signals are ultimately routed to, for example, a telephone connected to the land line network, or to a mobile telephone perhaps operating in another part of the world covered by a different gateway, or perhaps to computer system. The signals may encode voice communications such as telephone conversations or data communications such as, for example, facsimile transmissions, Internet connection signals, etc. The subscriber unit 12 may be a hand-held mobile telephone, a mobile telephone mounted in a boat, train or airplane, a laptop computer, a personal data assistant or any other suitable communications unit provided with the proper equipment for communicating with the gateway via the satellite fleet.
A single gateway may handle all telecommunications traffic within an area covering as much as 2000 by 3000 kilometers. FIG. 2 illustrates an exemplary coverage area 18 for a gateway 20 operating in Europe. As can be seen, the coverage area encompasses many countries. Each country typically has one or more service providers. Depending upon the implementation, each service provider may operate only within one country or perhaps only within a portion of one country. Such restrictions may result from physical limitations on the capability of the service provider system or from contractual or other legal constraints. For example, even though operationally capable of doing so, a service provider in France may not be contractually and/or legally allowed to handle mobile communications for a subscriber unit operating in Italy and vice versa. Hence, for subscriber units in France (such as exemplary unit 22), the gateway may need to route communications through a French service provider such as TE.SA.M.; whereas, for subscriber units in Italy, the gateway may need to route communications through an Italian service provider such as Finmeccanica. Further, as represented by arrow 24, subscriber units may move from one country to another. Even within a single country the gateway may need to selectively route communications to different service providers depending upon the location of the subscriber unit within the country. Moreover, the operator of the subscriber unit may be contractually obligated to use certain service providers in certain locations or may be subject to other legal constraints. In addition to any contractual limitations that may prevent telephone connections from the subscriber unit from being connected to particular service providers, the user of the subscriber unit may simply have certain preferences regarding which services provider to employ.
For these and other reasons, it may be desirable for the gateway to be able to reliably coordinate access among numerous service providers and among numerous mobile telephone users over a large geographical area. Heretofore, no adequate system has been developed for that purpose, particularly one which takes into account user preferences. Aspects of the present invention are directed toward providing such a system.